1. Field of Invention
The present invention relates to a lantern structure. More particularly, the present invention relates to a lantern structure that uses the light emitting diode (LED) as the light source.
2. Description of Related Art
There are many lamplight applications on a vehicle, such as headlights, turn signals, reverse lights and taillights. The lamps and lanterns on the vehicle must not only be pleasing to the eye but also must fulfill the more important purposes of lighting and warning, such that the safety of passengers and pedestrians can be maintained. Vehicle lamplight requirements have become more and more stringent with the progress of the automobile industry.
Light bulbs, such as halogen light bulbs, are the most general and typical light source used in the lanterns of vehicles. Because the purpose of light bulbs is only to radiate light, and the light radiated from the light bulbs does not allow for much variation with respect to the irradiating scope and the light color, the light bulb design is not flexible. Several disadvantages in using light bulbs have gradually become apparent with the introduction of newer lighting technologies. For example, the light bulb consumes more power and generates more heat than newer lighting technologies, raising the power consumption of the vehicle and thus degrading power efficiency. In addition, the higher brightness light bulb or the fluorescent tube may seriously pollute the environment because it contains hazardous materials such as mercury. Moreover, the casing of the light bulb and fluorescent tube is made of glass, which is easily damaged by a violent shaking or impact, drastically reducing the lifetime of the lights.
Many of these drawbacks are overcome by the light emitting diode (LED); the LED has a smaller volume, a lower power consumption, a lower heat generation and many available colors (wavelengths) of light that can be chosen. Thus, the LED has become increasingly more popular in vehicle lantern applications. However, the luminous intensity of the LED is lower than the light bulb under the same power consumption; therefore, how to effectively make good use of the light radiated from the LED is very important.
FIG. 1 shows an LED lantern structure for a vehicle. The vehicular lantern comprises many luminous bodies in general, such as the luminous bodies 102 and 104. Both the luminous bodies 102 and 104 comprise an LED 106, a condensing lens 108 surrounding the LED 106 and a transparent radiating cover 110. The LED 106 is used to act as the light source for the whole vehicular lantern. The condensing lens 108 is used to gather the light dispersed from the LED 106 and focus it on a lantern cover 118. The radiating cover is used to protect the LED 106.
In practice, the vehicular lantern must sometimes achieve pantoscopic irradiating, that is to say, the light must not only be radiated straight out from the surface of the vehicular lantern but also must be dispersed for burdening the irradiating scope of the vehicular lantern in order to bring more attention to pedestrians and other vehicles. Therefore, the luminous bodies 102 and 104 in the vehicular lantern shown in FIG. 1 are arranged as a stair-shape for burdening the irradiating scope of the vehicular lantern.
The foregoing vehicular lantern structure still has some problems. The material of the lantern cover 118 exhibits some reflectivity in general; therefore, a part of the light 112 radiated from the luminous bodies 102 and 104, such as a light 114, will be reflected back into the inside of the vehicular lantern when the light 112 passes through the lantern cover 118. Because the light 112 is naturally scattered, the brightness of the vehicular lantern is somewhat reduced, and furthermore, the light 114 is reflected back into the inside of the vehicular lantern, further reducing the brightness. In another aspect, although the stair-shape lantern structure can increase the irradiating scope and angle of the light, the volume of the whole lantern will be relatively increased, too. Moreover, further loss of light occurs because a part of the light radiated from the luminous body 104, such as a light 116, is obstructed by the luminous body 102. In addition, the design of the lantern structure is not flexible because the number of bright points is bound to the number of luminous bodies in the lantern structure. Thus, the number of luminous bodies cannot be easily reduced.
According to the foregoing shortcomings, a more economical and more efficient vehicular LED lantern structure is needed.